Carburetor



Dec. 5, 1933. F. c, MockP 1,937,709 f Y CARBURETOR Filed Aug. lso, 1950 INVENTOR.

(,"y J1 l ATTORNEY ating temperatures.

Patented Da. s, 1933 PATENT'4 OFFICE 1.

CARBURETOB Frank C. Mock, East Orange, N. J., assignmto Bendix Stromberg Carburetor Company, South Bend, Ind., a corporation of Illinois Application August 30, 1930. Serial No. 478,847

' Y 12 Claims. (Cl. 261-34) f This invention pertains to carburetors for movbile internal combustion engines and more particularly has reference to acceleration pumps for supplying additional fuel whenever the throttle is quickly opened` This invention is an improvement in the type of acceleration pump disclosed in the copending application oi Don Cole, Ser. No. 189,983, filed May 9, 1927, of common ownership with this l0 application.

While the acceleration pumps disclosed in the copending application referred to work satisfactorily under ordinary conditions when the temperature under the hood does not exceed d F., difficulty is experienced in summer Weather when the hood temperature ranges from 1GO" F to i30 F. or higher. Under these conditions, with present automobile iuels which contain fractions forming vapor bubbles between 10d F. and 139 F., considerable amounts of vapor accumulate in the piston chamber or dome. Ii the acceleration pump is operated while the chamber is partially lled with this vapor', as' soon as the outlet communication is opened the vapor escapes in one sudden rush driving all the iuel in the passages before it and giving so rich a mixture that the engine `misses and stumbles. Another ldisadvantage oi the previ'ous type pumps mentioned vis that at slightly Warmer temperatures, they evacuate entirely and give no accelerating charge whatever.

An object of this invention is to overcome the above diiiiculties by providing an acceleration pump Whose fuel outlet is belowthe point of egress of fluid past the piston so that no vapor is ejected into the fuel passages during the operation of thev pump. l

Another object of my invention is to provide an improved acceleration pump-in which even though the liquid fuel content-thereof is half boiled awayno vapor is ejected into the mixing chamber of the carburetor during the operation of the pump.

Anotherobject "my invention is to provide an acceleration pump in which the discharge of vide. an acceleration pump that is automatically self-scavenging as to fuel vapor formed therein by boiling of light fractions at the higher oper- A still further object ,of my invention is to frlprovide'an acceleration pump having an upe turned fuel cupwhich is not evacuated of fuel by the vaporizaticn of part of the fuel only, so that' there is always some liquid accelerating charge available.

I With these and other objects in view which 6@ may be incident to my improvements, my invention consists in the combination and arrangement of elements hereinafter described and illustrated in the accompanying drawing in Winch:

Figure 1 is a side elevation of a carburetor @5 containing' my improved acceleration pump, partly broken away to show the pump in vertical section.

Figure 2 is a fragmentary sectional view on a larger scale of my improved pump at the be- 7G ginning of its downward stroke.

Figure 3 is a similar view showing the piston at the end of its downward stroke.

Figure 4 is a similar view showing the piston on its return upward stroke.

Figure 5 shows the position of the piston and m pump upon the completion of its return strobe, and

Fig. 6 is a, sectional view on the line 6-6 oi Fig. 2.

Referring particularly to Figure 1, the reierm ence numeral 1 denotes the body of a conventional carburetor which has the usual air intake 2, mixing chamber 3, and mixture outlet 4 controlled by a throttle valve 5. yFixed upon the throttle shaft 6 is a cam 7 which bears upon and actuates a lever 8, pivoted at 9 and connected to a link 10 which in turn is connected to anin verted closed cylinder 11 by a ball and Socke' 4joint 24. Cylinder 11 forms a part of my improved acceleration pump and contains a loosefitting hollow piston 12 which is mounted upon a fixed stud 13 and adapted to reciprocate thereon and within the `cylinder 11.

Stud 13 is screwed into the bottom wall of 91 main jet 17 projecting into the mixing chamber` 3 of the carburetor. -The upper part of stud 13 is in the form of .1an upturned cup 18 which 1, communicates through metering orices 19 with the inside of hollow piston 12. The outside of cup i8 is hexagonal in shape so as to provide edges which form guides for piston 12` and in-` termediate spaces for the iiowof v4liquid fuel from 1,

'. orices 19 to cross passages 20 which communicate with axial bore 15 aforesaid The lower inner part oi hollow piston 112 is conical in shape so as to seat tightly on the conical shoulder 21- of cup 18 and close 20 1 when piston 12 Ais in its upper position.A Piston I. Whenever the throttle 5 is opened, cam 7,'

'inder and piston.

12 is held on its seat 21 by a spring 22 which pump will never fail t'odeliver an accelerating 10 fuelfrdm cup 18 through metering orifices 19 is chargewhen desired.- Since the ow'of liquid controlled 4by gravity, it may be graduated as desired.- Theintake of the lpump from the float chamber 14 is through the space between the cylinder 11 and piston 12.

AThe operation of my deviceVY is as follows.

through 'lever 8 and link 10, depressescylinder 11-. But if the opening .of the throttle 5 lis gradual the liquid and vapor contents escape through thespace between the cylinder walls and piston 12 and the piston'12` is not moved from its seat 21. Consequently thereisvno discharge from the pump into the mixing chamber 3 of the carburetor. If, however, the opening of the throttle 5 is sudden, there is not time enough for the escape of fluid through the space between the cyl- Accordingly a pressure is-at once built up in cylinder 11 which unseats piston 12, opening passage 20' and forcing the liquid which drains from cup 18 through orifice 19 through bore 15,.passageway 16 and main jet 17 into mixing chamber 3.

At low speeds and light loadsthe cylinder 1,1

remains in its upper position and thepiston 12.

ascent of piston 12. Also during the ascending stroke of piston l2, the vapor in the dome of cylinder 11 will be forced out into float chamber 14 through, the space between cylinder 11 and piston.12, and since passages 20 are kept liquid sealed by the liquid in piston 12, no vapor can escape through bore 15, passageway 16, jet 17 into mixing chamber 3. Also between conditions in Figures 3 and 4, the liquid in cup 18 has been gradually draining out so as to keep the liquid in cylinder.12 at or slightly above the level of the passages 20. g

When the throttle is closed the cylinder 11 is raised and a fresh charge of fuel is drawn into the cylinder under vconsiderable suction. Under these conditions, as shown in Figure 5, bubbles will promptly form again since the temperature of the fuel has not been changed, but the bubbles will collect in the top of cylinder 11 and'conditions will assume the status illustrated in Figure' 2 and the cycle above described will be repeated upon the next operation of the pump.

From the foregoing' description, it is clear that I have devised anovel means of overcoming the present difficulties in the operation' of acceleration pumps due to the formation and discharge of vapor. l

I While I have shown and described the pre- -ferred embodiment of my invention, I desire is held to its seat 21 by the spring 22. As bubbles f orm in the liquid-within cylinder 11 due to the boiling of the light fractions at higher operating temperatures and to the entrained air which is always present in pumped liquid fuel, theygo to the top partially displacing the liquid i-n cylinder -'and the compression of vapor in the domeI space of the cylinder forces the piston 12 down as far as it will go, compressing the spring 22 which is very light and of negligible force as regards varying the volume of the vapor in the cylinder,

'after which cylinder 11 may move downwardly it to be understood that I do not confine my-v self 'to the constructional details disclosed as these may be readily changed and modified by those skilled in the art without departing from the spirit o f my invention or exceeding the scope of the appended claims.

I claim:

`l. In a carburetor, an acceleration pump comprising a cylinder in the form of a' bell having anopen mouth at .its lower end, a piston reciprocating in said cylinder with a loose fit providing a channel for the escape of fuel vapor from said cylinder through .said mouth, and an outlet for liquid fuel from said cylinder below the point of egress of lfluid pastsaid piston whereby no vapor is ejected ,into said liquid fueloutlet duringthe operation of the pump.

2. In a carburetor, an accelerationpump comprising a cylinder in the form of a bell having an'open mouth at its lower end, a piston loosely tting in said cylinderl and providing a channel for the escape of vapor from said cylinder through said mouth, a liquid fuel outlet from vsaid cylinder, and means for sealing said outlet with liquid 'fuel until said cylinder is completely emptied, whereby vapor is prevented from escaping through said outlet during the operation of the pump.

j 3. In a carburetor, an acceleration pumpcom-'- prising a cylinder, a piston loosely fitting in.

ally pass down between the cylinder 11 andpis-- ton 12 and escape into the float chamber` 14 which is'suitablyventedto, the atmosphere. At

Ythe same time, whatever liquid is. present in cylinder 1'1 and cup 18 will escape through passages.

20 and some 'small-amount between the piston 12 'Iena stud 1a. I

After the throttle 5 nes been'held open .e nale while, sprlng`22 will begin to return piston 12 to its-seat 21 and conditins will be as shown in ,Figure 4. During this phase, any liquid held in the bottom of piston 12 will be forced out through passages 20 by the pressure of vapor in of vapor from's'aid cylinder, a liquid fuel outlet from said cylinder, means for preventing the escape of vapor through said outlet, and

4'. In a carburetor, aliquid fuel'naccelerating' pump comprising 'a hollow fixed stud `terminatcylinder 11 as the-liquid level is raised by the drical.piston reciprocating f on said stud and engaging the edges of the hexagonal walls of said cup whereby channels are formed between fuel therebetween.

par

memos 5. In a carburetor, an acceleration pump coinprising a cylinder, a cup within said cylinder for holding a reserve supply of liquid fuel, and a metering orice in said cup whereby said liquid fuel is discharged at a regulated rate regardless of the vapor pressure in said cylinder.

6. In a carburetor, an acceleration pump comprising an upwardly extending outletmember, a fuel container having an aperture fitted over the outlet member and adapted to reciprocate thereon, and a fuel reservoir formed on the outlet member.

7. In a carburetor having a float chamber, an acceleration pump comprising an outlet member projecting into the float chamber, an openended inverted fuel container reciprocable on the outlet member, and a fuel reservoir asso-l ciated with the. outlet member and' designed to furnish a flow of fuel for sealing the outlet port during operation of the pump.

8. In a carburetor, an acceleration pump comprising an outlet member terminating in a fuel reservoir and having an outlet-port below the reservoir, a piston reciprocably mounted on the outlet member and designed to close said outlet port when in one position, and a fuel container reciprocably mounted on the piston. l

9. In a carburetor, an acceleration pump comprising 4an outlet member terminating in a fuel reservoir having a restricted outlet, said outlet com rising `an outlet member, a cylinder reciprocable `onv the outlet member, and pressure relief means between the outlet member andA cylinder operative to permit escape of vapor from the cylinder while retaining an acceleration charge of liquid`fuel therein.

11. In a carburetor, a fuel reservoir, and an acceleration pump supplied from the fuel reservoir and 'comprising an outlet member', a cylinder reciprooable on the outlet member, andpressure relief means interposed between the outlet member and cylinder operative upon the development of a predeterminedfpressure within the cylinder to permit escape of vapor from the cylinder to the fuel reservoir while retaining an acceleration charge of liquid fuel therein;k

12. A device as defined in claim l1, wherein the pressure relief means comprises a yielding piston slidable relative to the outlet member and cylinder `and operative to close the outlet member. 1

FRANK C. MOCK. 

